Reuter Stokes Proportional Counter

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9a3daa
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Reuter Stokes Proportional Counter

Post by 9a3daa » Thu Aug 30, 2012 10:37 am

Respect.

I have Reuter Stokes Proportional Counter - Model: RS-P7-0805-127
Length: 20 cm with HN connector. Sensitive length: 16 cm Diameter: 2.5 cm

Writes this: Proportional Counter
Fill gas Ar (Argon)
Pressure: 23 cm Hg (0.3Bar)
Max.Volt 1200

I contacted GE and they told me this:

The part RS-P7-0805-127 would be a B-10 lined proportional counter, filled with ~0.8bar of Argon as quench gas. According to our files, this detector was made in 1976.

The reason why I was puzzled by your request is that this particular detector is not designed for gamma radiation. On the contrary, it is a neutron detector, with a very good gamma discrimination.

Question: How can discriminate gamma, and measure neutrons?
On my instrument I have only threshold potentiometer.
Now only receives pulses from gamma background (80-100CPM)
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Richard Hull
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Re: Reuter Stokes Proportional Counter

Post by Richard Hull » Thu Aug 30, 2012 3:59 pm

Interesting. I have never seen this type of boron lined tube. I do know that the bias voltage is critical and is often below 900 volts and that a good pre-amp is needed with careful setting of the discriminator. Boron lined tubes can be great, but a simple instrument is not going to work them correctly.

You may have to assemble a NIM setup and make your own pre-amp or cobble up a system from scratch. I have no doubt that the tube is a nice find and worth all the effort that it would take to make it count neutrons.

A good neutron source would be nice to have in working with discriminating this tube.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Tyler Christensen
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Re: Reuter Stokes Proportional Counter

Post by Tyler Christensen » Thu Aug 30, 2012 4:08 pm

I had pretty good luck getting B-10 tubes to work in the past.

Like Richard said, you need to have voltage control in addition to discrimination level control. At a certain voltage, the gamma level was vastly below that of neutrons. 50V lower, there was nothing and 50V higher the gamma signal would be huge and way above that of neutrons.

Pretty much all I did to set it up was set the discrimination at a fairly low setting and turn up the voltage until gamma set it off. Then back it down about 50V, and then it was good to measure neutrons.

Of course, if you have manufacturer suggested voltages just use them and set the discriminator to cut out gamma. Might still require some tweaking of the voltage, though.

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9a3daa
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Re: Reuter Stokes Proportional Counter

Post by 9a3daa » Thu Aug 30, 2012 4:08 pm

Gas is not B-10. Its filled with Argon.
And written: 1200V max

And tube is bad. Has a narrow plateau. When the voltage is below 1150V - no pulses.
When the voltage is above 1250V goes to saturation.
When the voltage is exactly 1200V gamma background radiation is 80 - 100CPM

And sometimes alone knows to stop giving impulses @ 1200V.

Once this tube is 20 years ago worked at +150 degrees Celsius
It was a measure of the thickness of the asphalt, with powerful Cobalt 60 source.

I think the tube is dead, because today sometimes will not giving impulses @ 1200V.


And I have AmBe neutron source - 60uCi
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Chris Bradley
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Re: Reuter Stokes Proportional Counter

Post by Chris Bradley » Thu Aug 30, 2012 5:39 pm

Arni,

There is tons of stuff about this in these forums, which will explain what you are seeing with the tube.

Rather than ask a question, try helping yourself first and read.

But, well, if you are now sure this means the tube is dead, you can send it to me if you like, and I'll pay you $5 on top of postage, then I'll 'recycle' it for you properly. You don't want boron getting just anywhere now, do you?

The introduction says to post an intro on yourself. We hope to see that soon.

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Richard Hull
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Re: Reuter Stokes Proportional Counter

Post by Richard Hull » Thu Aug 30, 2012 5:44 pm

Tyler gave good info as the voice of experience. The voltage to detect neutrons is no where near 1200 volts. You need to put a thermal neutron source near the tube or put the tube in a moderator jacket and use a fast neutron source. Next, using a rather high gain, high impedance preamp, look at its output with an oscilloscope as you raise the voltage from about 700 volts.

At some point, you will see the neutron pulses appear. If you keep advancing the voltage higher, you will see a flood of pulses. Back off the voltage until you see just the neutron pulses again and leave the voltage there. To double check, remove the neutron source. The pulses should virtually stop.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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9a3daa
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Re: Reuter Stokes Proportional Counter

Post by 9a3daa » Thu Aug 30, 2012 5:47 pm

No! Its NOT B-10 gas - Filled with Argon - see picture
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9a3daa
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Re: Reuter Stokes Proportional Counter

Post by 9a3daa » Thu Aug 30, 2012 5:52 pm

Is 60uCi Ambe neutron source enough to get impulses from preamplifier?
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Chris Bradley
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Re: Reuter Stokes Proportional Counter

Post by Chris Bradley » Thu Aug 30, 2012 5:55 pm

Yeah, we know that Arni. No-one's said otherwise. The inside is lined with boron, that's how B-10 tubes are made .... and your next outburst is ...?

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Chris Bradley
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Re: Reuter Stokes Proportional Counter

Post by Chris Bradley » Thu Aug 30, 2012 5:57 pm

From just 60uCi of Am? .. I can't see how you'll measure that over background with a little B-10 tube like this. [...YES... its ARGON filled... we know!!!]

Read the other threads, you'll see how to estimate the n rate. So, again to say.. good idea to read the threads first, than ask questions without reading.

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